Conventional clothes washing machines include an agitator which oscillates during the washing cycle to facilitate the cleaning of clothes. The oscillation of the agitator is achieved through a series of linkages and gears. More particularly, an input shaft is connected to a drive motor and an output shaft is connected to the agitator. An eccentric gear is driven through an arcuate path by a series of gears connected to the input shaft. The eccentric gear is operatively connected to the output shaft, such that the rotary motion from the input shaft is converted into the oscillating motion of the agitator. The off-center linkages require a counterweight for balance. The nonalignment of the shafts produces undesirable side loading on the shafts and gears. The off-center shafts and counterbalance also necessitate a larger transmission housing.
A substantially different washing machine transmission is disclosed in U.S. Pat. Nos. 2,161,604 and 2,222,329 issued in the name of Watts. The Watts patents show opposing rack gears operatively connected to coaxially aligned input and output shafts to convert the rotary motion of the input shaft to an oscillation motion for the output shaft and connected agitator in a clothes washing machine. However, the devices disclosed in the Watts' patents are not believed to have been ever commercialized due to a problem of binding between the rack gears and the output pinion. Such binding necessarily resulted from the lack of radial or side-to-side movement of the rack gears relative to the output pinion.
Accordingly, a primary objective of the present invention is the provision of an improved dual drive transmission which converts rotary movement to oscillating movement.
A further objective of the present invention is the provision of a dual drive transmission for a clothes washing machine having a reduced size, without reducing load carrying capabilities.
Another objective of the present invention is the provision of a dual drive transmission wherein the shafts are co-axially aligned and the gears are equally spaced from the shaft axes.
A further objective of the present invention is the provision of a dual drive transmission wherein gear loading is equalized.
Another objective of the present invention is the provision of rack gears which convert rotary motion to oscillating motion without binding.
Still another objective of the present invention is the provision of an improved dual drive transmission normally having pairs of opposite gears on opposite sides of the drive shaft, and wherein the gears on one side of the shaft may be removed to provide a single drive transmission for reduced capacity machines having lesser power requirements.
A further objective of the present invention is the provision of an improved transmission having an anti-backup mechanism.
These and other objectives will become apparent from the following description of the invention.